Lrp1 Regulation of Pulmonary Function. Follow-Up of Human GWAS in Mice

Vicenin-2 in Suhuang antitussive capsule attenuates mitophagy-dependent ferroptosis via LRP1 for treating post-infectious cough

ETHNOPHARMACOLOGICAL RELEVANCE

Suhuang antitussive capsule (SH) is the only clinically approved traditional Chinese patent medicine for the treatment of post-infectious cough (PIC). During the past decade, our lab has conducted intensive researches on SH, including its efficacy and mechanism on PIC, and determined that SH has favorable anti-inflammatory, antitussive, expectorant, and anti-asthmatic pharmacological effects. Recently, we found that vicenin-2 (VIC-2) could be detected in SH and showed activity in vitro primary screening on PIC.

AIM OF THE STUDY

To investigate the therapeutic effects of VIC-2 on PIC and its potential mechanisms, and want to elucidate VIC-2 as one of the efficacious components of SH.

MATERIALS AND METHODS

The PIC mouse model was established with lipopolysaccharide (LPS)-induced combined cigarette smoke (CS)-exposed ICR mice, while the in vitro assay was constructed to induce BEAS-2B cells with cigarette smoke extract (CSE). The therapeutic effects of VIC-2 on PIC in vitro and in vivo were assessed by pathological sections, cough assay, immune cell counting, and quantitative-polymerase chain reaction (Q-PCR). The mechanisms of VIC-2 on ferroptosis and mitophagy in PIC were further explored by cell viability assay, Prussian blue staining, lipid peroxidation assessment, confocal laser scanning microscopy, and western blotting. Subsequently, virtual docking, cellular thermal shift assay (CETSA), and drug affinity responsive target stability (DARTS) verified the target relationship between VIC-2 and LDL receptor-related protein 1 (LRP1). In addition, the link between LRP1 and mitophagy-dependent ferroptosis was explored by knocking down LRP1.

RESULTS

VIC-2 significantly improved lung inflammation, oxidative stress, and airway remodeling in PIC and inhibited mitophagy-dependent ferroptosis, confirming that it is one of the antitussive components of SH for the treatment of PIC. LRP1 is one of the pharmacological targets of VIC-2, in which VIC-2 exerted the above effects through up-regulating LRP1 by influencing the LRP1-Parkin interaction. The blockade of LRP1 reversed the both in vitro and in vivo pharmacological activities of VIC-2. Furthermore, our results showed for the first time that defects in LRP1 lead to ferroptosis.

CONCLUSION

This study demonstrates that VIC-2 inhibits mitophagy-dependent ferroptosis via LRP1 for the treatment of PIC, constituting one of the antitussive components of SH.

Astrocytic LRP1 enables mitochondria transfer to neurons and mitigates brain ischemic stroke by suppressing ARF1 lactylation

Low-density lipoprotein receptor-related protein-1 (LRP1) is an endocytic/signaling cell-surface receptor that regulates diverse cellular functions, including cell survival, differentiation, and proliferation. LRP1 has been previously implicated in the pathogenesis of neurodegenerative disorders, but there are inconsistencies in its functions. Therefore, whether and how LRP1 maintains brain homeostasis remains to be clarified. Here, we report that astrocytic LRP1 promotes astrocyte-to-neuron mitochondria transfer by reducing lactate production and ADP-ribosylation factor 1 (ARF1) lactylation. In astrocytes, LRP1 suppressed glucose uptake, glycolysis, and lactate production, leading to reduced lactylation of ARF1. Suppression of astrocytic LRP1 reduced mitochondria transfer into damaged neurons and worsened ischemia-reperfusion injury in a mouse model of ischemic stroke. Furthermore, we examined lactate levels in human patients with stroke. Cerebrospinal fluid (CSF) lactate was elevated in stroke patients and inversely correlated with astrocytic mitochondria. These findings reveal a protective role of LRP1 in brain ischemic stroke by enabling mitochondria-mediated astrocyte-neuron crosstalk.

The Biology and Function of Tissue Inhibitor of Metalloproteinase 2 in the Lungs

Tissue inhibitors of matrix metalloproteinases (TIMP) are a family of four endogenous proteins that primarily function to inhibit the activities of proteases such as the matrix metalloproteinases (MMP). Altered MMP/TIMP ratios are frequently observed in several human diseases. During aging and disease progression, the extracellular matrix (ECM) undergoes structural changes in which elastin and collagens serve an essential role. MMPs and TIMPs significantly influence the ECM. Classically, elevated levels of TIMPs are suggested to result in ECM accumulation leading to fibrosis, whereas loss of TIMP responses leads to enhanced matrix proteolysis. Here, we outline the known roles of the most abundant TIMP, TIMP2, in pulmonary diseases but also discuss future perspectives in TIMP2 research that could impact the lungs. TIMP2 directly inhibits MMPs, in particular MMP2, but TIMP2 is also required for the activation of MMP2 through its interaction with MMP14. The protease and antiprotease imbalance of MMPs and TIMPs are extensively studied in diseases but recent discoveries suggest that TIMPs, specifically, TIMP2 could play other roles in aging and inflammation processes.

Assessing the contribution of rare genetic variants to phenotypes of chronic obstructive pulmonary disease using whole-genome sequence data

RATIONALE

Genetic variation has a substantial contribution to chronic obstructive pulmonary disease (COPD) and lung function measurements. Heritability estimates using genome-wide genotyping data can be biased if analyses do not appropriately account for the nonuniform distribution of genetic effects across the allele frequency and linkage disequilibrium (LD) spectrum. In addition, the contribution of rare variants has been unclear.

OBJECTIVES

We sought to assess the heritability of COPD and lung function using whole-genome sequence data from the Trans-Omics for Precision Medicine program.

METHODS

Using the genome-based restricted maximum likelihood method, we partitioned the genome into bins based on minor allele frequency and LD scores and estimated heritability of COPD, FEV1% predicted and FEV1/FVC ratio in 11 051 European ancestry and 5853 African-American participants.

MEASUREMENTS AND MAIN RESULTS

In European ancestry participants, the estimated heritability of COPD, FEV1% predicted and FEV1/FVC ratio were 35.5%, 55.6% and 32.5%, of which 18.8%, 19.7%, 17.8% were from common variants, and 16.6%, 35.8%, and 14.6% were from rare variants. These estimates had wide confidence intervals, with common variants and some sets of rare variants showing a statistically significant contribution (P-value < 0.05). In African-Americans, common variant heritability was similar to European ancestry participants, but lower sample size precluded calculation of rare variant heritability.

CONCLUSIONS

Our study provides updated and unbiased estimates of heritability for COPD and lung function, and suggests an important contribution of rare variants. Larger studies of more diverse ancestry will improve accuracy of these estimates.

Role of the LRP1-pPyk2-MMP9 pathway in hyperoxia-induced lung injury in neonatal rats

OBJECTIVES

To study the role of the low-density lipoprotein receptor-related protein 1 (LRP1)-proline-rich tyrosine kinase 2 phosphorylation (pPyk2)-matrix metalloproteinases 9 (MMP9) pathway in hyperoxia-induced lung injury in neonatal rats.

METHODS

A total of 16 neonatal rats were randomly placed in chambers containing room air (air group) or 95% medical oxygen (hyperoxia group) immediately after birth, with 8 rats in each group. All of the rats were sacrificed on day 8 of life. Hematoxylin and eosin staining was used to observe the pathological changes of lung tissue. ELISA was used to measure the levels of soluble LRP1 (sLRP1) and MMP9 in serum and bronchoalveolar lavage fluid (BALF). Western blot was used to measure the protein expression levels of LRP1, MMP9, Pyk2, and pPyk2 in lung tissue. RT-PCR was used to measure the mRNA expression levels of LRP1 and MMP9 in lung tissue.

RESULTS

The hyperoxia group had significantly higher levels of sLRP1 and MMP9 in serum and BALF than the air group (P<0.05). Compared with the air group, the hyperoxia group had significant increases in the protein expression levels of LRP1, MMP9, and pPyk2 in lung tissue (P<0.05). The hyperoxia group had significantly higher relative mRNA expression levels of LRP1 and MMP9 in lung tissue than the air group (P<0.05).

CONCLUSIONS

The activation of the LRP1-pPyk2-MMP9 pathway is enhanced in hyperoxia-induced lung injury in neonatal rats, which may be involved in the pathogenesis of bronchopulmonary dysplasia.

LDL receptor-related protein 1 and its interacting partners in tissue homeostasis

PURPOSE OF REVIEW

LDL receptor-related protein 1 (LRP1) is a multifunctional protein with endocytic and signal transduction properties due to its interaction with numerous extracellular ligands and intracellular proteins. This brief review highlights key developments in identifying novel functions of LRP1 in liver, lung, and the central nervous system in disease pathogenesis.

RECENT FINDINGS

In hepatocytes, LRP1 complexes with phosphatidylinositol 4-phosphate 5-kinase-1 and its related protein to maintain intracellular levels of phosphatidylinositol (4,5) bisphosphate and preserve lysosome and mitochondria integrity. In contrast, in smooth muscle cells, macrophages, and endothelial cells, LRP1 interacts with various different extracellular ligands and intracellular proteins in a tissue-dependent and microenvironment-dependent manner to either enhance or suppress inflammation, disease progression or resolution. Similarly, LRP1 expression in astrocytes and oligodendrocyte progenitor cells regulates cell differentiation and maturation in a developmental-dependent manner to modulate neurogenesis, gliogenesis, and white matter repair after injury.

SUMMARY

LRP1 modulates metabolic disease manifestation, inflammation, and differentiation in a cell-dependent, time-dependent, and tissue-dependent manner. Whether LRP1 expression is protective or pathogenic is dependent on its interaction with specific ligands and intracellular proteins, which in turn is dependent on the cell type and the microenvironment where these cells reside.

The molecular mechanism of LRP1 in physiological vascular homeostasis and signal transduction pathways

Interactions between vascular smooth muscle cells (VSMCs), endothelial cells (ECs), pericytes (PCs) and macrophages (MФ), the major components of blood vessels, play a crucial role in maintaining vascular structural and functional homeostasis. Low-density lipoprotein (LDL) receptor-related protein-1 (LRP1), a transmembrane receptor protein belonging to the LDL receptor family, plays multifunctional roles in maintaining endocytosis, homeostasis, and signal transduction. Accumulating evidence suggests that LRP1 modulates vascular homeostasis mainly by regulating vasoactive substances and specific intracellular signaling pathways, including the plasminogen activator inhibitor 1 (PAI-1) signaling pathway, platelet-derived growth factor (PDGF) signaling pathway, transforming growth factor-β (TGF-β) signaling pathway and vascular endothelial growth factor (VEGF) signaling pathway. The aim of the present review is to focus on recent advances in the discovery and mechanism of vascular homeostasis regulated by LRP1-dependent signaling pathways. These recent discoveries expand our understanding of the mechanisms controlling LRP1 as a target for studies on vascular complications.

Learning a genome-wide score of human-mouse conservation at the functional genomics level

Identifying genomic regions with functional genomic properties that are conserved between human and mouse is an important challenge in the context of mouse model studies. To address this, we develop a method to learn a score of evidence of conservation at the functional genomics level by integrating information from a compendium of epigenomic, transcription factor binding, and transcriptomic data from human and mouse. The method, Learning Evidence of Conservation from Integrated Functional genomic annotations (LECIF), trains neural networks to generate this score for the human and mouse genomes. The resulting LECIF score highlights human and mouse regions with shared functional genomic properties and captures correspondence of biologically similar human and mouse annotations. Analysis with independent datasets shows the score also highlights loci associated with similar phenotypes in both species. LECIF will be a resource for mouse model studies by identifying loci whose functional genomic properties are likely conserved.